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Enikő Réka Fábián and Áron Kótai

Abstract

During our investigation lath martensite was produced in low carbon steels by austenitization at 1200 °C/20 min, and the cooling of samples in ice water. The samples were tempered at a range of temperatures. The tempering effects on microstructure and on mechanical proprieties were investigated. Some samples with lath martensite microstructure were cold rolled and heat treated at different temperatures. Recrystallization was observed after heat treatment at 600-700 °C.

Open access

Krisztina Horicsányi, Lilla Asztalos, Dóra Károly and Éva Fazakas

Abstract

During implantation, stents are delivered in crimped state to the narrowed lesion, where they are expanded to the desired size by the balloon. Due to insufficient size selection or high resistance to plaque, the stent is often widened by the expansion pressure to a level greater than the nominal pressure specified by the manufacturer. Depending on the degree of overpressure, the nominal diameter of the stent may change by several tenths of a millimetre. Numerous studies have dealt with the physiological effects of overexposure and stenogenic stress, but so far no studies have been carried out to investigate the stent coating and corrosion properties of the stent. In our research a widely used drug-eluting, platinum-chromium alloyed steel stent was observed with an inflation pressure of 12 and 18 bar. Scanning electron microscopy revealed lesions of the coating and potentiodynamic tests were performed to determine the corrosion rate.

Open access

Agata Felusiak and Paweł Twardowski

Abstract

The present paper presents comparative results of the forecasting of a cutting tool wear with the application of different methods of diagnostic deduction based on the measurement of cutting force components. The research was carried out during the milling of the Duralcan F3S.10S aluminum-ceramic composite. Prediction of the toolwear was based on one variable, two variables regression Multilayer Perceptron(MLP)and Radial Basis Function(RBF)neural networks. Forecasting the condition of the cutting tool on the basis of cutting forces has yielded very satisfactory results.

Open access

János Kónya and Klaudia Kulcsár

Abstract

The 3D block products presented in this study are used in dental surgery to provide bone replacement for patients who do not possess a sufficient amount of bone tissue for implantation. If dental implants are supported by a proper amount of allografts, the mastication ability of the patient can be totally restored. The required bone replacement for the insertion of dental implants is a reconstruction utilising lyophilized human bone tissue treated with alveolar and mandibular odontological albumin. This study puts emphasis on the analysis, planning and processing of CBCT images, and on the machining and production three-dimensional albumin-coated allograft. The study also extends to former and current bone grafting techniques, and provides a review on BoneAlbumin and the selection of suitable materials. This paper also investigates the domestic and international bone grafting market. Furthermore, it contains a case study and conclusions.

Open access

Enikő Bitay, Irén Kacsó and Erzsébet Veress

Abstract

ZrO2 doped Na-Ba-borosilicate glasses suitable as matrix materials for HLW immobilization were synthesized and corrosion behaviour was investigated in different aqueous media. Hydrolytic stability is increased with the doping level until 5 mol %; above this value the glass vitrification tendency is strongly intensified. Unexpectedly, ZrO2 doping diminished the corrosion stability in 1M HCl solution, and low ZrO2 content showed a low corrosion resistance in 1M Na2CO3 solution also. Doping effect was negligible in case of synthetic seawater. The glass structure is significantly stabilized by the integration of the 30% UO3 added.

Open access

Tünde Kovács and Péter Pinke

Abstract

Ultrasonic welding is very useful for joining thin metal sheets [1, 2]. The effect of ultrasound on microstructure is currently not well understood because the changes produced depend very much on the welding parameters and the properties of the metal being considered. Thin sheets formed by cold rolling acquire a special grain structure. During the welding process the heat produced causes recrystallization; even where heat is not applied in the joining process the recrystallization process alters the mechanical properties within the heat affected zone (HAZ). The mechanical properties of the welded samples depend on the microstructure. In this work we analyse the ultrasonic welding effect on the joint and the HAZ [3, 4].

Open access

Martyna Wiciak, Paweł Twardowski and Szymon Wojciechowski

Abstract

In this paper, the problem of tool wear prediction during milling of hard-to-cut metal matrix composite Duralcan™ was presented. The conducted research involved the measurements of acceleration of vibrations during milling with constant cutting conditions, and evaluation of the flank wear. Subsequently, the analysis of vibrations in time and frequency domain, as well as the correlation of the obtained measures with the tool wear values were conducted. The validation of tool wear diagnosis in relation to selected diagnostic measures was carried out with the use of one variable and two variables regression models, as well as with the application of artificial neural networks (ANN). The comparative analysis of the obtained results enable.

Open access

S. Islak

Abstract

In this study, wear properties of FeW-B4C coatings produced by tungsten inert gas (TIG) process on the AISI 1060 steel were investigated. TIG process was selected because it is a cost-effective approach for melting-based coatings. The treated surfaces were evaluated and characterized by means of scanning electron microscope (SEM), X-ray diffraction analysis, and electron dispersive spectrometry (EDS). The microhardness and wear experiment were also performed by using a microhardness machine and ball-on-disk tribometer. SEM observations showed that the obtained coating had a smooth and uniform surface. According to XRD analysis, borides and carbides phases formed in the coatings. The wear behavior of the coatings was compared with ball-on-disc configuration wear tests, at the same conditions. Average coefficient of friction values of the coatings were obtained at relatively low levels.

Open access

M. Piasecka, K. Strąk and B. Grabas

Abstract

The paper describes applications of the vibration-assisted laser surface texturing and spark erosion process as methods of modifying properties and structures of metal surfaces. Practical aspects of the use of produced surfaces in the heat exchanger with a minichannel have been described. Compared with smooth surfaces, developed metal surfaces obtained by vibration-assisted laser surface texturing and electromachining show more effective heat transfer. The local heat transfer coefficient for the saturated boiling region obtained for developed surfaces had the values significantly higher than those obtained for the smooth plate at the same heat flux. The experimental results are presented as the heated plate temperature (obtained from infrared thermography) and relationships between the heat transfer coefficient and the distance along the length of the minichannel for the saturated boiling region.

Open access

R. Bęczkowski, J. Wróbel and A. Kulawik

Abstract

In the paper, the regeneration process of the material in grade C45 using the MAG welding was analysed. The effect of preheating on the properties of the regenerated layers was determined. Preheating technology was used to facilitate the process of regeneration and minimize the risk of imperfections. The use of numerical methods allows one to observe the direction of changes in the properties, structures and emerging stresses and accompanying strains of the elements depending on the temperature applied for preheating. Modeling of the stress state in the element made of medium carbon steel during the regeneration process was performed on original software based on the finite element method. The implemented numerical model consists of three basic elements – thermal phenomena, mechanical phenomena and phase transformations in the solid state. The performed numerical analysis made determining the optimum heating conditions possible, so that the material in the area of joint didn’t show tendency to create structural notches associated with the stress state.